Can low-fusing glass application affect the marginal misfit and bond strength of Y-TZP crowns?

To evaluate the effect of different surface treatments on the marginal misfit and retentive strength between Y-TZP crowns and an epoxy resin. Forty (40) epoxy resin (G10) abutments (height: 5mm, conicity: 60, finish line: large chamfer) with equal dimensions were milled and included in polyurethane to simulate the periodontal ligament. Next, 40 Y-TZP crowns (thickness: 1mm) were milled (Cerec in Lab) and randomly divided into four groups (n=10) according to the surface treatment: GS(glaze spray), GP(glaze powder/liquid), P(zirconia primer) and RS(tribochemical silica coating). The conditioned surfaces were cemented with dual self-adhesive cement, light cured and submitted to thermomechanical cycling (2x106, 100N, 4Hz, 5 degrees /55 degrees C). Marginal misfit was analyzed by a stereomicroscope and SEM. Retentive strength test was performed (1mm/min) until crown debonding. Glaze layer thickness was also performed to GS and GP groups. Marginal misfit data were analyzed by Kruskal Wallis and Dunn tests; one-way ANOVA and Tukey (5%) analyzed the tensile strength data. The marginal misfit of the GS (48.6+/-19.9mum) and GP (65.4+/-42.5mum) were statistically lower than the RS (96+/-62.9mum) and P (156+/-113.3mum) (p=0.001). The retentive strength of the GP (470.5+/-104.1N) and GS (416.8+/-170.2N) were similar to the P (342.1+/-109.7N), but statistically higher than those of the RS (208.9+/-110N). The GS and GP glaze layer was 11.64mum and 9.73mum respectively. Thus, glaze application promoted lower marginal discrepancy and higher retentive strength values than conventional techniques.